A number of applications have been established making use of medical devices, which can be delivered by way of minimally invasive methods in a patient. An example of such a medical device is a heart valve prosthesis.
Various replacement heart valves for aortic, mitral and tricuspid heart valves are currently available. In particular in the context of aortic heart valves replacement valves a side effect is the necessity of pace maker implantation in many implantations and devices. The requirement of a pacemaker can be as high as 30% in state of the art device implantation. This does not only have the drawback of another surgery and medical device with all its negative implications for the patient but also imposes increased cost in the context of such a heart valve replacement therapy. Accordingly there is a need to avoid or at least reduce the rate of pacemakers in such treatments.
Another problem often occurs when trying to achieving a correct implantation and positioning of the prosthesis at the target site in order to fully and reliably exhibit the prosthesis' function.
A particular example is a catheter-based aortic valve prosthesis consisting of a self-expanding stent and a valve known for treating aortic insufficiency. Such heart valve prostheses are positioned at the aortic annulus to replace the endogenous aortic valve. The aim is to correctly position the heart valve prosthesis with regard to the aortic annulus and the endogenous cusps.
WO2004/019825 describes an aortic prosthesis wherein the prosthesis exhibits feelers which are meant to be deployed first and placed into the aortic cusps. Once the feelers have been placed within the cusps the stent is deployed to complete the implantation. The entire implant procedure is guided by fluoroscopic imaging. The stent and feelers are visible under fluoroscopy. The aorta, aortic valve, and left ventricle are visualized indirectly by injecting contrast medium through an angiographic catheter into the left ventricle and ascending aorta. During valve deployment the angiographic catheters are retracted to avoid interference between the stent and the angiographic catheter. Thus, the operator mainly relies on tactile feedback for feeler placement.
In case of a transfemoral valve replacement, the tactile feedback may be inconsistent due to the tortuosity of the access vessels and the curvature of the aortic arch. As a result, the prosthesis may not be placed sufficiently correct at its target site. In case a prosthesis is applied that uses feelers, cusp positioners, hooks, rims or similar means to provide for precise positioning and/or targeting the endogenous leaflet cusps, these means may not be correctly positioned and/or they may be placed away from the base of the cusps or may damage the cusps.
There exists thus the need for better guiding the placement of the valve prosthesis and to avoid damage of the endogenous heart tissue and in particular cusp damage or perforation.
Another issue is leakage of blood between the replacement heart valve and the endogenous tissue e.g. at the annular ring of the aortic heart valve. Known prostheses try to improve leak tightness by applying or forming a ring or band along the annular ring and cover the prosthesis by a symmetric band made of biological or synthetic tissue. Some disclosures try to improve the leak tightness with the combination of the outward force of the prosthesis and the symmetrical band aligned along the annular ring. This approach is commonly used and it is acknowledged that a symmetrical sealing ring is a useful approach, which serves the purpose, however, this approach is not always 100% successful.
Yet another issue is the need for pacemaker implantation after heart valve replacement therapy. In currently available therapies and heart valve prostheses a considerable number of patients require a pacemaker implantation after heart valve replacement therapy. Currently there are a number of replacement heart valves on the market like the Sapiens HVT, the Lotus device, the Corevalve device or the Symetis device all for aortic heart valve replacement with a minimally invasive approach. The percentages of the requirement for pacemaker transplantation vary between these products. It is acknowledged that the pacemaker requirement is unwanted and makes yet another surgery necessary including all its negative implications.
Accordingly, there is a need to provide for methods and replacement heart valves with a reduced need of pacemaker implantation.
Hence it is one object to provide for a replacement heart valve therapy with reduced pacemaker rate.
It is another object to provide for a means and a method for save positioning replacement heart valves into an individual's body at a target site.
It is yet another object to be able to visually control the correct positioning of a replacement heart valve.
It is another object to provide heart valve prostheses with good or even advantageous leak tightness features.
It is yet another object to provide for a replacement heart valve therapy wherein the replacement heart valve is engineered in a manner so as to reduce or even substantially avoid the disadvantages of the prior art, or to provide for a replacement heart valve that combines the advantages of being capable of secure and correct positioning and at the same time exhibiting a reduced need for pacemaker implantation.
It is yet another object to provide for a replacement heart valve prosthesis which has improved properties or/and which exhibits advantageous features with respect to the pacemaker need, e.g., a reduced pacemaker need vis-à-vis known devices or a pacemaker rate that is acceptable, easy positioning, and/or good leak tightness features.